Recently, an electronic equipment, that conforms to the transmission standard called HDBaseT (registered trademark), has been developed which enables transmission and reception of video signals and audio signals and supply of electric power between a transmitter apparatus and a receiver apparatus connected to each other by a local area network (LAN) cable (see Patent Literature 1).
In the electronic equipment that conforms to HDBaseT, the receiver apparatus receives the video signals and audio signals transmitted from the transmitter apparatus over the LAN cable and reproduces the received video signals and audio signals.
In a system that uses the HDBaseT transmission, a video signal, an UART, a remote controller signal, a LAN signal, a GPIO operation and the like are input to an integrated circuit (IC) of the transmitter apparatus, and the signals are encoded into a signal format that conforms to HDBaseT in the IC and transmitted. The converted signals are received on an IC in the receiver apparatus and decoded in the IC into the original signals. The ICs in the transmitter apparatus and the receiver apparatus, that conform to the HDBaseT transmission scheme, may further conform to the USB transmission scheme for handling universal serial bus (USB) signals.
An apparatus capable of transmitting USB signals typically has an USB-A terminal to which an USB DEVICE device such as a memory or a mouse is connected and an USB-B terminal to which an USB HOST device such as a personal computer (PC) is connected, and uses one of the USB-A terminal and the USB-B terminal. Whether the USB-A terminal or the USB-B terminal is used depends on the voltage set at a discrimination terminal when the apparatus is activated. The voltage at the discrimination terminal is set by a switch or the like.
In a transmission system that uses USB signals, the USB HOST device operates as a controlling device, and the USB DEVICE device operates as a controlled device. The USB HOST device controls the USB DEVICE device by USB signals. Therefore, the signal processing method performed in a case where the USB HOST device is connected to the apparatus is different from the signal processing method performed in a case where the USB DEVICE device is connected to the apparatus. As a result, it is necessary to switch the control method (operation mode).
In a system that uses the HDBaseT transmission with superimposed USB signals, the transmitter apparatus and the receiver apparatus each determine the USB processing operation depending on the voltage status at the discrimination terminal described above when the power source is turned on, and perform a setting to switch the firmware to operate. For example, if the transmitter apparatus is set for connection to an USB HOST device, and the receiver apparatus is set for connection to an USB DEVICE device, the USB HOST device such as an PC connected to the transmitter apparatus can read data or the like from the USB DEVICE device such as an USB memory connected to the receiver apparatus.